Instructional Objective: 1. Learn the atomic models 2 Instructional Objective: 1.Learn the atomic models 2.Learn the atomic structure and elements.

History of the Atomic Model The Greek Model Dalton’s Model Thomson’s Model Rutherfords Model Bohr’s Model The Wave-Particle Model

The Greek Model Proposed around 400 B.C. By the Greek Philosopher Democrats Called them “Atomos”, in Greek means can’t be divided or destroyed.

John Dalton’s Model Proposed the Atomic Theory in 1803 All atoms are made up of solid indivisible particles. * Elements differ in their atom’s size

J. J. Thomson’s Model Proposed in 1897 “raisin bread”model Believed that protons and electrons were mixed together Known as the “plum pudding” or “raisin bread”model

Ernest Rutherford’s Model Proposed in 1907 after discovering atom’s nucleus Electrons move around a central nucleus containing protons. .

Niels Bohr’s Model Electrons move in energy levels around a central nucleus Electrons can only be in these energy levels.

Particle-Wave Model James Chadwick discovers neutron in 1935. Electrons are most likely found in energy levels

What is an Atom? *The smallest unit of a matter is known as an atom What is an element? An element is made up of only one kind of atom. What is a molecules ? Is the smallest unit of a compound What is a substance? any element or compound

Structure of an atom An atom is made up of a nucleus that contain protons and neutrons. And an outer orbit that contain electrons. -Protons are always positive in charge -Electrons are negative in charge -Neutrons are neutral or without any charge

Characteristics of an Atom Atom itself has no charge because protons are always equal to electrons. Ex: Sodium –Protons are 11 --Electrons are also 11 ( Positive and negative will cancel each other)

Properties of subatomic particles Protons, electrons and neutrons are the subatomic particles Protons are always positive in charge Electrons are negative in charge Neutrons are neutral or with out any charge

Difference between atomic mass and Atomic number Atomic mass: is the total number of protons and neutrons in the nucleus. Atomic number: Is the total number of protons

Element Block from periodic table 17 ---- atomic number Cl ---- Symbol Chlorine –Name 35.45 --- atomic mass or mass number 17 Cl Chlorine 35.45

Other Symbols to remember p+ →Proton(always positive charge) e- → electron (always negative in charge) N0 → Neutrons(zero charge) <→Less than > →greater than + → and or plus → → yield (s) → solid (l) → Liquid (g) → gas

ISOTOPES. Atoms of the same element that have different number of Neutrons. Ex: The most common isotope of hydrogen. -Hydrogen has no neutrons at all(1proton) -Deuterium, with one neutron. (1proton+1neutron) - Tritium, with two neutrons.(1proton+2 neutrons)                                                       

Isotopes can be written as the part of a chemical symbol Ex: 15 7N or Nitrogen – 15 ( 15 is the mass number and 7 is the atomic number) Ex: 3517Cl or Chlorine -35( 35 is the mass number and 17 is the atomic number) Close to the atomic mass, abundant is the element in that Isotope.

How are electrons arranged in an atom Electron Cloud The area in an atom where electrons are found Energy levels Is the place in the electron cloud Are in different distance from nucleus The closest to nucleus –less and weak Far away from nucleus –more and more powerful

The energy levels 1st- contain maximum 2 2nd- contain maximum 8 3rd- contain maximum 18 4th - contain maximum 32

Electron Configurations * Is the arrangement of electrons in the orbitals of an atom.

Electron configuration S orbit- 2 electrons P orbit-6 electrons D orbit-10 electrons F orbit – 14 electrons